1. Field of the Invention
The present invention relates to a character input device, an image forming apparatus provided with the character input device and a character key display method.
2. Related Art
In recent years, an image forming apparatus such as a copy machine, a facsimile machine, a multifunction peripheral and the like includes a character input device that displays a software keyboard, in which a plurality of character keys is arranged in a predetermined arrangement, on the touch screen (touch screen).
A user can input, for example, the user's name, a user ID, a password, an e-mail address, a name for an image to be saved, a file name, a title, and the like using the character input device.
However, due to a limited display area on the touch screen, the software keyboard displayed on the touch screen tends to have character keys (buttons) smaller in size than character keys of a conventional hardware keyboard, and to have a character key arrangement largely different from that of a hardware keyboard. This causes a problem of difficulty in character input, and even a user accustomed to a hardware keyboard cannot smoothly input characters.
In order to solve such a problem, as Prior Art 1, a Latin alphabet character (romaji) input device is disclosed in which, during Latin alphabet character input with a touch screen, after input of a consonant key, only vowel keys and double consonant keys that may follow the consonant are highlighted. Such a configuration is expected to prevent input of an invalid character sequence in Latin alphabet characters.
As Prior Art 2, an alphabet input system with character prediction using a keyboard is disclosed for an electronic apparatus provided with a keyboard and a display screen. In this system, a plurality of selection control keys is separately provided in the keyboard, and a plurality of subsequent input candidates with reference numbers is displayed in a subsequent area of the display screen, in response to previous alphabet input. In addition, this system is configured such that a desired candidate can be selected and input from the subsequent input candidates. Such a configuration is expected to reduce an average number of keystrokes by using the alphabet input system with character prediction along with a conventional alphabet input.
In addition, as Prior Art 3, a character input device is disclosed in which a plurality of characters is assigned to virtual keys displayed on a display unit, and when a user operates an operating unit to select a virtual key and a character assigned thereto, a plurality of candidate words related to the selected character is displayed. Such a configuration is expected to allow a user to input characters rapidly without stress, and allow an efficient use of a display region on a display screen.
However, the character input device of Prior Art 1 is targeted at Latin alphabet character input and cannot be applied to all languages that are generally input, for example English words and Japanese words in hiragana and katakana.
In addition, technologies disclosed in Prior Arts 2 and 3 require a subsequent display region that displays a plurality of subsequent input candidates or virtual keys corresponding to an input operation by a user, in addition to a display region that displays a normal software keyboard, leading to a problem of a need of extended display area of a touch screen.